Antistatic resin-made container and kit for production thereof

ABSTRACT

An antistatic resin-made container is formed by solution-bonding a plurality of resinous parts thereof to each other, preferably with acetonitrile as the solvent, wherein each resinous part is formed of an antistatic resin composition including (a) a polyacrylonitrile resin: 50-95 wt. % and (b) a hydrophilic polymer: 5-50 wt. %. The thus-formed antistatic resin-made container is suitable for accommodating a precision product, such as a photomask, or a semi-product thereof, which is produced in an extremely small number but requires a high level of antistatic property of the container therefor.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to an antistatic resin-made containersuitable for accommodating precision products or semiproducts thereofwhich are produced in a very small number but require a high level ofantistatic property, such as photomasks (including reticles) andpellicles as protective films for such photomasks, semiconductorwafer-related trial products, liquid crystal display (LCD)-related trialproducts, IC-product-related trial products, etc., and a kit forproduction of such an antistatic resin-made container.

Precision products such as photomasks as mentioned above extremely hateelectrostatic attraction of fine particles, and the transportation orstorage thereof is performed by using an antistatic resin-madecontainer. For providing such an antistatic resin-made container,conventional techniques of applying or kneading an antistatic agentcannot provide a persistent antistatic effect, so that the use of anantistatic resin composition comprising a hydrophilic polymer andanother thermoplastic resin has been studied in recent years forproviding a permanent antistatic resin. There have been introducedmethods of incorporating hydrophilic polymers, such as polyethyleneoxide, polyether-ester-amide and quaternary ammonium salt-containingcopolymers, into thermoplastic resins, such as polystyrene, ABS and PMMA(“Japan Society of Static Electricity”, Vol. 21, No. 5, pp. 212-219(1997)). Herein, “permanent anitistatic property” is unlike anon-persistent antistatic property which may be obtained by applicationof an antistatic agent or bleeding-out to the surface of a shapedarticle of an antistatic agent kneaded into an ordinary thermoplasticresin and can be remarkably reduced by wiping of the surface, but meansa permanently and persistently exhibited antistatic property which isdeveloped by an antistatic agent stably held inside a thermoplasticresin constituting a shaped product and is not essentially reduced bywiping of the shaped product.

As a preferred example of such a permanently antistatic resincomposition, the present applicant already developed a thermoplasticresin composition having permanent antistatic property and also goodtransparence, preferably by further incorporating an anionic surfactantinto a thermoplastic resin composition comprising a graft copolymer of arubber trunk polymer having an alkylene oxide group (Japanese PatentPublication (JP-B) 59-2462; corr. to GB-A 2070046).

While the function mechanism of the above-mentioned thermoplastic resincomposition exhibiting permanent antistatic property has not been fullyclarified as yet, it is considered that a rubber trunk polymercomprising a monomer having an alkylene oxide group and a conjugateddiene or an acrylate ester as one component is dispersed, at the time ofprocessing, in the graft component resin or a mixture of the graftcomponent resin and a thermoplastic resin as the matrix component in theform of mutual bridges, and an antistatic agent added thereto isselectively adsorbed principally by the rubber trunk polymer, so thatwhen a charging member contacts the shaped body, electric charges of theopposite polarity are moved principally through the rubber trunk polymerphase adsorbing the antistatic agent to be quickly accumulated at thecontact surface, thereby dissipating and neutralizing the charges givenby the charging member.

The above-mentioned antistatic resin comprising a hydrophilic polymerand another thermoplastic resin is generally formed into a container byinjection molding or sheet forming such as vacuum forming orair-pressure forming (hereinafter sometimes inclusively referred to as“injection molding, etc.”). However, the above-mentioned precisionproducts, such as photomasks (including reticles) and pericles asprotective films therefor, LCD-related trial products andIC-product-related trial products, or semi- or half-products thereof,which require a high antistatic property, are generally characterized inthat they are extremely expensive (e.g., over several millions yen perpiece of product) but are produced in only a small number for a varietyof designs. Accordingly, it is extremely uneconomical for providing anexpensive mold for injection molding or sheet molding for forming acontainer for each of such precision (semi-)products. For this reason,there has been taken a measure to form a somewhat larger-sized containercommonly used for several sizes of precision (semi-)products byadjusting positions of precision (semi-)product-holding members disposedinside the container, but the increase of unnecessary internal space inthe container increases the possibility of attachment of dirt, such asfine particles, onto the precision (semi-)products.

SUMMARY OF THE INVENTION

Accordingly, a principal object of the present invention is toeconomically provide a container for a precision (semi-)product which isproduced in a very small number but requires a high antistatic property,while retaining a level of antistatic property comparable to aninjection-molded product or a sheet-molded product.

According to the present invention, there is provided an antistaticresin-made container for a precision (semi-)product having a structurecomprising a plurality of resinous parts bonded with a solvent to eachother, wherein each of the plurality of resinous parts comprises anantistatic resin composition comprising (a) a polyacrylonitrile resin:50-95 wt. % and (b) a hydrophilic polymer: 5-50 wt. %.

In the present invention, a shaped product (e.g., in the form of asheet) of an antistatic resin composition obtained by combining with ahydrophilic polymer (b) another thermoplastic resin comprising apolyacrylonitrile resin(a) as a principal resin component to haveenhanced mechanical properties, such as rigidity and wear resistance, iscut into a plurality of parts, which are bonded to each other with asolvent having a dissolving power to a polyacrylonitrile resin, therebyforming a container for a precision (semi-)product exhibiting excellentantistatic property without resorting to injection molding or sheetforming. Herein, the term “solution bonding” refers to a technique ofbonding a pair of resinous parts to each other with a solvent of theresin while partly dissolving the faces to be bonded of the resinousparts, and the solution bonding is used instead of using a resinousadhesive for polyacrylonitrile resins (as disclosed in JP-A 60-53579 andJP-A 61-44966) in order to prevent the impairment of antistaticity ofthe entire container due to the formation of an insulating layer at thebonding boundary by the use of such a non-antistatic resin adhesive.

According to the present invention, there is also provided a kit forproducing an antistatic resin-made container, including (1) anantistatic resin sheet comprising (a) a polyacrylonitrile resin: 50-95wt. % and (b) a hydrophilic polymer: 5-50 wt. %, and (2) solventacetonitrile. By using the kit, the antistatic resin sheet is cut intosizes of parts suitable for storing a precision (semi-)product to becontained, and the parts are solution-bonded with each other, therebyallowing an order-made production of an antistatic resin containerhaving a size fitted for a precision (semi-)product and exhibiting alevel of antistatic property comparable to the one prepared by injectionmolding etc., without resorting to the injection molding, etc.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1A to 1C are three-directional views of an outer structure of amain body of an antistatic resin-made container according to anembodiment of the present invention, including FIG. 1A (an upper planview), FIG. 1B (a side view as viewed in a direction of arrow-headed B-Bline in FIG. 1A) and FIG. 1C (a side view as viewed in a direction ofarrow-headed C-C line in FIG. 1A)

DESCRIPTION OF PREFERRED EMBODIMENTS

Antistatic Resin Composition

The antistatic resin composition forming the antistatic resin-madecontainer of the present invention comprises (a) a polyacrylonitrileresin: 50-95 wt. %, and (b) a hydrophilic polymer: 5-50 wt. %.

(Polyacrylonitrile Resin)

As a principal re sin component of the antistatic resin composition, thepolyacrylonitrile resin (a) is used in combination with the hydrophilicpolymer (b) used in a relatively small amount to provide an antistaticresin shaped product with enhanced mechanical properties, such asrigidity and wear resistance, while retaining a necessary level ofantistatic property.

In the present invention, the term “polyacrylonitrile resin” is used toinclusively refer to a rigid resin comprising polymerized units ofunsaturated nitrites (including methacrylonitrile,α-chloro-acrylonitrile, etc., in addition to acrylonitrile) as aprincipal constituent of at least 30 wt. %, preferably 50 wt. % or more.As far as the condition is satisfied, the polyacrylonitrile resin cancontain polymerized units other than those of unsaturated nitritesinclusive of a rubbery component (preferably comprising a copolymer ofunsaturated nitrile) for improving the impact resistance. Representativeexamples thereof may include those produced by processes disclosed inJP-B 46-25005 and JP-B 49-32789, and commercially available product soldunder the name of “BAREX 210” (from BP Amoco).

The polyacrylonitrile resin (a) may preferably exhibit a flexuralrigidity of at least 2 GPa. The polyacrylonitrile resin (a) is used inan amount occupying 50-95 wt. %, preferably 80-95 wt. %, of theantistatic resin composition (with respect to its resin content) Below50 wt. %, desired mechanical properties cannot be attained, and thesolution-bonding strength is also impaired.

(Hydrophilic Polymer)

As the hydrophilic polymer (b) constituting the antistatic resincomposition for the antistatic resin-made container of the presentinvention together with the polyacrylonitrile resin (a), hydrophilicpolymers disclosed as permanent antistatic resins in the above-mentionedreference, “Japan Society of Static Electricity”, vol. 21, No. 5, pp.212-219, particularly in Table 6 on page 216, may be used. Suchhydrophilic polymers may be characterized as polymers which are solidand have a high ionic conductivity at room temperature. Specificexamples thereof may include: polyether-type hydrophilic polymers,inclusive of polyethylene oxide, polyether-ester-amide,polyether-amide-imide, ethylene oxide-epihalohydrin copolymer, and agraft copolymer of a rubber trunk polymer having a polyalkylene oxidegroup; quaternary ammonium salt-type hydrophilic polymers, such asquaternary ammonium salt-containing (meth)acrylate copolymers,quaternary ammonium salt-containing maleimide copolymers, and quaternaryammonium salt-containing methacrylimide copolymers; sulfonic acid-typehydrophilic polymers, such as poly-sodium styrenesulfonate; betaine-typehydrophilic polymers, such as carbobetaine graft copolymers; andpolymeric charge transfer combinant-type hydrophilic polymers. Among theabove, polyether-type hydrophilic polymers having (poly)alkylene oxidegroups including at least partially (poly)ethylene oxide groups, arepreferred, and particularly a graft copolymer basically identical to theone developed by the present applicant (JP-B 54-2462, corr. to GB-A2070446, the disclosure of which is incorporated herein by reference)and having the following composition is preferably used.

That is, a graft copolymer (A) obtained by graft-polymerizing (iv) 5 to95 wt. parts of at least one species of ethylenically unsaturatedmonomer onto a rubber trunk polymer in an amount of 5 to 95 wt. parts(giving a total of 100 wt. parts with the ethylenically unsaturatedmonomer), which rubber trunk polymer in turn is a copolymer of

-   -   (i) 50-95 wt. % of at least one monomer selected from conjugated        dienes and acrylate esters,    -   (ii) 5-50 wt. % of at least one species of monomers each having        an ethylenic unsaturation and 4 to 500 alkylene oxide groups,        preferably including at least 4 ethylene oxide groups, and    -   (iii) 0-40 wt. % of at least one species of ethylenically        unsaturated monomer copolymerizable with the conjugated diene or        acrylate ester (i).

The hydrophilic polymer (b) is used in an amount of 5-50 wt. %,preferably 5-20 wt. %, of the antistatic resin composition (with respectto its resin content). Below 5 wt. %, the desired antistatic effectcannot be attained. In excess of 50 wt. %, the polyacrylonitrile resinis reduced in amount correspondingly to impair the mechanical propertiesincluding rigidity, and also the solution-bonding strength.

Within an extent that the polyacrylonitrile resin (a) and thehydrophilic polymer (b) satisfy the above-mentioned respectivecompositional ranges, another thermoplastic resin can be included in theantistatic resin composition of the present invention. Examples of suchanother thermoplastic resin may include: polyethylene, polypropylene,polyvinyl chloride, polyvinylidene chloride, aromatic vinyl polymers,nitrile resins, (meth)acrylic resins comprising homopolymers orcopolymers of (meth)acrylate esters, ABS(acrylonitrile-butadiene-styrene) resin, acrylonitrile-styrene resin,polycarbonate resin, polyamide resins, polyester resins, andfluorine-containing resins. It is preferred to use a resin having goodcompatibility with the hydrophilic polymer (a). However, such anotherthermoplastic resin should preferably be suppressed to at most 20 wt. %of the resin content of the antistatic resin composition so as to retainthe antistatic property, mechanical property and solution-bondingstrength characterizing the antistatic resin of the present invention.

In order to prevent the haze or discoloration with acidic gas or basicgas on the surface of the antistatic resin-made container of the presentinvention or the surface of the precision (semi-)product containedtherein, it is also preferred to incorporate a polyvalent metal compound(c) having a valence of at least 2 in the antistatic resin compositionof the present invention. Such a polyvalent metal compound (c) maypreferably be used in an amount of 0.001-0.5 wt. part more preferably0.001-0.3 wt. part, further preferably 0.001-0.1 wt. part, per 100 wt.parts of the total resin content in the antistatic resin. Below 0.001wt. part, the haze-prevention effect becomes scarce, and in excess of0.5 wt. part, the bleeding-out of the metal compound (c) per se isliable to be problematic.

The polyvalent metal compound (c) may be added at any time ofpolymerization, blending, shaping, etc. In the case of addition at thetime of blending or shaping, for example, a master batch containing themetal compound (c) at a concentration of, e.g., 10 wt. % may be added inan amount of 0.01-5 wt. parts per 100 wt. parts of the total resin.Examples of the polyvalent metal compound (c) having a valance of atleast 2, preferably 2-4, may include: metal salts inclusive of alkalineearth metal salts, such as magnesium chloride, calcium chloride,magnesium oleate and calcium stearate; and IIIA-group metal salts, suchas aluminum chloride and aluminum stearate; and also metal oxides, suchas titanium oxide, zinc oxide and tin oxide. The exact mechanism bywhich such a polyvalent metal compound prevents the occurrence of hazedue to an acidic gas or a basic gas has not been clarified as yet, butit is presumed the polyvalent metal forms a complex with adsorbed acidicgas or basic gas to obstruct the crystal growth of such a gaseoussubstance on a shaped product surface.

A surfactant (d) may be further added so as to be adsorbed on thehydrophilic polymer (a) to enhance the permanent antistatic property ofthe resultant antistatic resin composition, but can be omitted. In orderto provide a good heat resistance, it is preferred to use an anionicsurfactant having a thermal weight loss initiation temperature accordingto JIS-K7120 (hereinafter sometimes denoted by “Tng”) of at least 250°C. The thermal weight loss initiation temperature has been recognized tohave some degree of correlation with the structure of an anionicsurfactant, and examples of the anionic surfactant having a thermalweight loss initiation temperature of at least 250° C. may include:Alkylbenzenesulfonic acid salts, alkylnaphthalene-sulfonic acid salts,aliphatic acid salts, perfluoro-alkylsulfonic acid salts,trifluoromethane-sulfonic acid salts, and perfluoroalkylcarboxylic acidsalts.

The selection of metal species constituting an anionic surfactant alsohas a relation with the effect of the anionic surfactant as anantistatic agent, and for the purpose of the present invention, a saltof an alkaline metal having an atomic number of 19 (corresponding topotassium) or more is preferred because of a large ionic diameterthereof suitable for providing a necessary antistatic property at arelatively small amount of addition, and also in view of a shorter timefor blending with the polyacrylonitrile resin (a) and the hydrophilicpolymer (b) and better physical properties of the shaped product,particularly resistance to whitening with warm water.

The surfactant (d) may preferably be used in a proportion of 0.1-5 wt.parts per 100 wt. parts of the total resin content in the antistaticresin. Below 0.1 wt. part, the antistatic property-improving effect isscarce, and in excess of 5 wt. parts, the blending-out to the surface ofa shaped product becomes remarkable to provide undesirable properties ofthe shaped product.

The antistatic resin composition of the present invention can furthercontain additives, as desired, such as an ultraviolet absorber, athermal stabilizer, an antioxidant, a lubricant, a filler and dyes orpigments, in addition to the above-mentioned components, and theaddition of these can be effected at any time of polymerization,blending, shaping, etc.

The antistatic resin-made container of the present invention has astructure formed by solution-bonding a plurality of parts eachcomprising the above-mentioned antistatic resin composition to eachother. Each of the plurality of parts may be obtained as a shapedproduct of the antistatic resin composition or a cut product therefrom.The shape of the shaped product is basically arbitrary but may be asheet-form product according to a preferred embodiment in view of thelatitude of a user in cutting therefrom arbitrary shapes and sizes ofparts for forming a shape of container for accommodating a precision(semi-)product having arbitrary shape and size. Such a sheet product mayhave a thickness on the order of 0.5-100 mm, particularly 1-20 mm. Thesheet product may preferably have a flexural rigidity of at least 1.5GPa, particularly 2.0 GPa or higher; a wear resistance represented by aTaber abrasion (according to JIS K7204) of at most 200 mg, particularly150 mg or less; and an antistatic property represented by a volumeresistivity (JIS K6911; 23° C., 23% RH) of at most ca. 10¹¹ ohm.m,particularly ca. 10¹⁰ ohm.m or below.

The above-mentioned shaped product (e.g., in a sheet form) may beobtained by subjecting the antistatic resin composition to formingmethods, such as injection molding, extrusion or compression molding. Itis also possible to shape the resin composition into a sheet or filmhaving a smaller thickness, a tube, etc., if desired.

The antistatic resin-made container of the present invention may beobtained by solution-bonding a plurality of parts which may be a sheetproduct, for example, as mentioned above, as it is, if the sheet producthas a desired size, or parts obtained by cutting such a sheet productinto sizes corresponding to a precision (semi-)product to be containedtherein.

As a solvent to be used for the solution bonding, a good solvent for thepolyacrylonitrile resin (a) may be used, and among others, acetonitrilehaving a boiling point of 81.6° C. is preferred in view of readiness ofdrying after the solution bonding. However, acetonitrile is toxic tosome extent, the solution bonding should be performed by using aprotector in an environment of good ventilation.

The kit for producing an antistatic resin-made container according tothe present invention comprises at least one antistatic resin sheet(preferably having a size, e.g., including a side of at least 250 mm,suitable for providing arbitrary sizes of parts by cutting thereof)formed by shaping into sheet of the above-mentioned antistatic resincomposition, and acetonitrile (solvent) stored in a container. It isalso desirable to attach a handling note for the acetonitrile.

For example, for preparation of a rectangular antistatic resin-madecontainer for storing a generally rectangular or disk-shaped precision(semi-)product, an antistatic resin sheet forming a bottom plate havingnearly a shape of the container is cut out from an antistatic resinsheet in the kit, and four bar-shaped parts having lengths of 4 sides ofthe bottom plate and a width corresponding to or a little larger thanthe thickness of the precision (semi-)product are cut out also from suchan antistatic resin sheet in the kit and are solution-bonded onto thefour sides of the bottom plate to provide a main body of the container,which is then covered with a lid member formed in a similar manner asthe main body to complete the container.

For the solution bonding in the above-mentioned case, for example,acetonitrile is applied in a small amount (e.g., ca. 160 g/m²) ontofaces to be bonded of the bar-shaped parts, and the parts are put alongand against the sides of the bottom plate under a pressing force of ca.5 Pa, followed by holding for ca. 1 min. under warming at ca. 40° C. asdesired to evaporate the solvent acetonitrile and standing for ca. 24hours so that a desired bonding strength is attained. The bondingstrength (JIS K6850; 23° C., tensile speed=5 mm/min.) may preferably beat least 7 MPa, particularly 10 MPa or higher.

Incidentally, in the present invention, a container is formed by bondingparts thereof not by using a resinous adhesive but according to thesolution bonding in order to avoid a local lowering in antistaticity byuse of a resinous bonding agent since there are few adhesive resinsshowing good antistaticity.

The thus-formed antistatic resin-made container of the present inventionis most suited for containing precision products or semi-productsthereof, which are produced in a very small number but require a highlevel of antistatic property, such as photomasks (including reticles)and pericles as protective films for such photomasks, semiconductorwafer-related trial products, LCD related trial products,IC-product-related trial products, etc.

EXAMPLES

Hereinbelow, the present invention will be described more specificallybased on Examples, wherein “part(s)” means “part(s) by weight”.

As a polyacrylonitrile resin (a), “BAREX 210” (flexural rigidity=3.38GPa, made by BP Amoco) was used. As a hydrophilic polymer (b), oneprepared in the following example was used.

Production of Hydrophilic Polymer

(a) A rubber trunk polymer-forming composition: Butyl acrylate 39.0part(s) Styrene 20.3 ″ Allyl methacrylate 0.7 ″ Methoxypolyethyleneglycol 10.0 ″ methacrylate (ii) (having averagely ca. 23 ethylene oxidegroups) Formaldehyde sodium sulfoxylate 0.08 ″ t-Butyl hydroperoxide 0.1″ Iron (III) ethylenediamine- 0.005 ″ tetraacetate Dihydrogen disodiumpyrophosphate 0.05 ″ Tetrasodium pyrophosophate 0.05 ″ Sodiumdodecylbenzenesulfonate 0.5 ″ Deionized water 290 ″

-   -   was charged and stirred at 50° C. for 4 hours in a reaction        vessel equipped with a stirrer, a thermometer and a pressure        gauge. Latex of a rubber trunk polymer having an average        particle size of 80 nm was obtained at a yield of 99% or higher.

(b) To the above latex of rubber trunk polymer (70 parts as solidmatter), a mixture of ethylenically unsaturated monomer (iv): Methylmethacrylate 24.0 part(s) Styrene 3.7 ″ Acrylonitrile 2.0 ″ Normal-octylmercaptan 0.3 ″ Formaldehyde sodium sulfoxylate 0.08 ″ t-Butylhydroperoxide 0.1 ″ Deionized water 70 ″was added, and the mixture was aerated with nitrogen and subjected tograft copolymerization at 50° C. for 4 hours. The latex was taken outand warmed at 70° C., and 1000 parts of hydrochloric acid aqueoussolution (concentration: 1.5 wt. %) at 70° C. was added to causeprecipitation. After dewatering and washing, the precipitate was driedto obtain a white powdery hydrophilic polymer (b).Antistatic Resin Composition and Measurement of Properties

100-40 parts of the above polyacrylonitrile resin (a), 0-60 parts of theabove hydrophilic polymer (b) and 0-0.3 part of potassiumnonafluorobutane-sulfonate as an anionic surfactant, were blended invarious ways to obtain 6 types of compositions.

Then, each composition was kneaded on an 8 inch-roll kneader (made byKansai Roll K.K.) and formed at 140-180° C. into 10 sheets each withplanar sizes of 1000 mm×300 mm and a thickness of 0.5 mm. Then, the 10sheets were pressed at 180-200° C. by a press-forming machine (made byShinto Kinzoku Kogyosho K.K.) to form an antistatic resin sheetmeasuring planar sizes of 250 mm×250 m and a thickness of 5 mm. Varioussamples were cut out from the antistatic resin sheet and used for thefollowing measurements.

(Volumetric Intrinsic Resistivity)

An antistatic resin sheet sample of 50 mm×50 mm in planar sizes and 5 mmin thickness was formed for each composition and, after moistureconditioning at a temperature of 23° C. and a humidity of 23% RH for 3days, subjected to measurement of a volumetric intrinsic resistivity byusing an ultra-super insulation meter (“SM-10E”, made by To a DempaKogyo K. K.) according to JIS K6911.

(Bonding Strength)

Two antistatic resin sheets each measuring 100 mm×25 mm in planar sizesand 5 mm in thickness (according to Shape and size (2) of a test piece(bonding plate) shown in FIG. 2 of JIS K6850) were formed for eachcomposition, and 50 mg of acetonitrile (as a bonding solvent) wasapplied in planar sizes of 12.5 mm×25 mm (area: 312.5 mm). Then, the twosheets were held under a pressing force of 5 Pa for 1 min., followed bystanding at a temperature of 23° C. and a humidity of 50% RH for 3 days.Then, by using a tensile tester (“AUTOGRAPH AG-200E”, made by ShimadzuSeisakusho K.K.), two ends of the bonded test pieces were chucked forholding with chucking planar sizes of 37.5 mm×25 mm and pulled at atensile speed of 5 mm/min. until the test pieces were broken to measurea bonding strength.

The component ratios and the measurement results of volumetric intrinsicresistivity and bonding strength for the respective compositions areinclusively shown in Table 1 below. TABLE 1 Composition (parts) Poly-Volumetric acrylo- Hydro- Intrinsic Bonding nitrile philic Resistivity*²Strength*³ Example resin (a) Polymer (b) KNFBS*¹ (Ω · m) (MPa) Comp. 1100 0 0 1 × 10¹³ 12 1 95 5 0.3 1 × 10¹¹ 12 2 92 8 0.3 1 × 10¹⁰ 11 3 9010 0.3 8 × 10⁹ 10 4 88 12 0.3 6 × 10⁹ 7 Comp. 2 40 60 0.3 1 × 10⁹ 1*¹KNFBS: potassium nonafluorobutanesulfonate*²Measured according to JIS K6911 (23° C., 23% RH)*³Measured according to JIS K6850 (23° C., 5 mm/min.)

In view of the above Table 1, it is understood that antistatic resincompositions with good antistatic property (i.e., low volumetricintrinsic resistivity) and bonding strength in combination were obtainedin the prescribed compositional ranges according to the presentinvention with respect to the polyacrylonitrile resin (a) andhydrophilic polymer (b).

Production of Container

From an antistatic resin sheet measuring 250 mm×250 mm in planar sizesand 5 mm in thickness formed from the antistatic resin composition ofExample 3 above, an outer structure of a main body of a container for a6-inch photomask having inner sizes of 230 mm×230 mm×depth 50 mm asshown in FIGS. 1A (top plan view) and 1B and 1C (side views as viewed inthe directions of B-B line and C-C line in FIG. 1A respectively) wasproduced in the following manner.

Thus, from the antistatic resin sheet of 250 mm×250 mm in planar sizesand 5 mm in thickness,

-   -   1 bottom sheet 1 of 240 mm×240 mm in planar sizes and 5 mm in        thickness,    -   2 side sheets 2 of 240 mm×50 mm in planar sizes and 5 mm in        thickness, and    -   2 side sheets 3 of 230 mm×50 mm in planar sizes and 5 mm in        thickness, were cut out as parts for providing a container.        After applying acetonitrile at a rate of 160 g/m² onto each        bonding face of the side sheets 2 and 3, the side sheets 2 and 3        were disposed as shown in FIGS. 1A-1C (with dashed lines        representing bonding boundaries) and were held under a pressing        force of 1 Pa for 1 min., followed by standing at 230° C. and        50% RH for 3 days, to form an outer structure of a main body (to        be combined with a lid member having a similar structure) as        illustrated in FIGS. 1A-1C.

The above-prepared container structure was dropped from a height of 75cm onto a concrete-surfaced floor so that a side wall thereof wasdirected downwards, whereas no breakage was observed at the bondingboundaries.

Separately, from a container structure prepared in the same manner asabove, 10 bar-strip samples each measuring 50 mm×5 mm in planar sizesand 5 mm in thickness were cut out so as to include a bonding boundaryand, after being moisture-conditioned at 23° C. and 23% RH for 3 days,were subjected to measurement of volumetric intrinsic resistivity byusing an ultra-super insulation meter (“SM-10E”, made by To a DempaKogyo K.K.), thereby exhibiting a volumetric intrinsic resistivity of8×10⁹ ohm.m on an average:

From the above results, it is understood that a container exhibiting agood bonding strength and a good antistatic property including a bondedpart (boundary) thereof.

As described above, according to the present invention, a plurality ofresinous parts comprising an antistatic resin composition formed of apolyacrylonitrile resin (a) and a hydrophilic polymer in appropriateproportions are solution bonded with each other preferably by usingacetonitrile as the solvent, whereby it becomes possible to provide anantistatic resin-made container suitable for accommodating precisionproducts or semiproducts thereof which are produced in a very smallnumber but require a high level of antistatic property, such asphotomasks (including reticles) and pericles as protective films forsuch photomasks, semiconductor wafer-related trial products, LCD-relatedtrial products, IC-product-related trial products, etc., and also a kitfor production of such an antistatic resin-made container.

1. An antistatic resin-made container for a precision (semi-)producthaving a structure comprising a plurality of resinous parts bonded witha solvent to each other, wherein each of the plurality of resinous partscomprises an antistatic resin composition comprising (a) apolyacrylonitrile resin: 50-95 wt. % and (b) a hydrophilic polymer: 5-50wt. %.
 2. An antistatic resin-made container according to claim 1,wherein the antistatic resin composition comprises 80-95 wt. % of thepolyacrylonitrile resin (a) and 5-20 wt. % of the hydrophilic polymer(b).
 3. An antistatic resin-made container according to claim 1, whereinthe hydrophilic polymer (a) is a polyalkylene oxide group-containingpolymer.
 4. An antistatic resin-made container according to claim 3,wherein the hydrophilic polymer (b) is a graft-copolymer obtained bygraft-polymerizing (iv) 5 to 95 wt. parts of at least one species ofethylenically unsaturated monomer onto a rubber trunk polymer in anamount of 5 to 95 wt. parts (giving a total of 100 wt. parts togetherwith the ethylenically unsaturated monomer), which rubber trunk polymerin turn is a copolymer of (i) 50-95 wt. % of at least one monomerselected from conjugated dienes and acrylate esters, (ii) 5-50 wt. % ofat least one species of monomers each having 4 to 500 alkylene oxidegroups and an ethylenic unsaturation, and (iii) 0-40 wt. % of at leastone species of ethylenically unsaturated monomer copolymerizable withthe conjugated diene or acrylate ester (i).
 5. An antistatic resin-madecontainer according to claim 1, wherein the antistatic resin compositionfurther comprises a surfactant.
 6. An antistatic resin-made containeraccording to claim 1, wherein the antistatic resin composition furthercomprises a polyvalent metal compound.
 7. An antistatic resin-madecontainer according to claim 1, wherein the polyacrylonitrile resin (a)exhibits a flexural rigidity of at least 2 GPa.
 8. A kit for producingan antistatic resin-made container, including (1) an antistatic resinsheet comprising (a) a polyacrylonitrile resin: 50-95 wt. % and (b) ahydrophilic polymer: 5-50 wt. %, and (2) solvent acetonitrile.
 9. A kitaccording to claim 8, wherein the antistatic resin sheet has thicknessof 1-20 mm.
 10. A kit according to claim 8 wherein the antistatic resinsheet has a flexural rigidity of at least 1.5 GPa, a Taber abrasion ofat most 200 mg and a volumetric intrinsic resistivity of at most 10¹¹ohm.m.